Head cleaning device

ABSTRACT

A head cleaning device for use in a magnetic recording and reproducing apparatus comprises a cleaning roller in which a lubricant with an excellent lubricating action under low humidity conditions impregnates the soft material. This lubricant compensates for the drop in the natural lubricating action resulting from a moisture deficiency, and therefore prevents the production of seized deposits. Furthermore, the head cleaning device comprises a first cleaning portion impregnated with polymer resin and abrasive particles, and a second cleaning portion comprising only a soft material, the second cleaning portion can remove by wiping any abrasive particles or deposits left on the magnetic head surface immediately after the abrasive cleaning action of the first cleaning member.

This application is a division of application Ser. No. 08/417,646, filedApr. 5, 1995, now U.S. Pat. No. 5,602,705, which is a continuation of08/076,571 filed on Jun. 14, 1993 now U.S. Pat. No. 5,453,893.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a head cleaning device for cleaning amagnetic head for use in a magnetic recording and reproducing apparatusand, more particularly, to a head cleaning device for removing depositsadhering to such magnetic head therefrom.

2. Description of the Prior Art

Reproducing with high reliability the signal recorded to magnetic tapeis an essential requirement for any magnetic recording and reproducingapparatus. After extended operation, however, magnetic particles,binder, resin, and other constituents of the magnetic tape separate fromthe tape and adhere to the head surface in contact with the magnetictape. This results in a variety of problems relating to theelectromagnetic conversion characteristics of the magnetic head,particularly reduced output, clogging, and signal dropout.

Various methods of removing these deposits from the sliding contactsurface of the magnetic head have been proposed in, for example, U.S.Pat. No. 4,462,056 which was issued to Kara Jul. 24, 1984 and U.S. Pat.No. 5,012,376 which was issued to Joannou et al. These methods make itpossible to remove deposits with a relatively weak force acting on themagnetic head surface. Under low humidity conditions, however, seizeddeposits with a bonding strength greater than the relatively weak forceapplied by the above methods are also formed from the magnetic tape ontothe sliding surface of the magnetic head, resulting in the occurrence ofso-called brown strain on the magnetic head surface. As a result, theoperating range of these methods is limited.

The brown stain cited in this invention is described briefly below.Moisture in the air is absorbed by the surfaces of the variouscomponents associated with the relative movement of the magnetic tape tothe magnetic head, which rotates at high speed, and contributes to thesmooth movement of the tape relative to the magnetic head by acting as alubricating film. In low humidity conditions, however, the contributionof ambient moisture to this smooth movement is reduced, increasing thecoefficient of friction between the tape and head, and increasing thedegree of direct contact between the tape and head.

Particulate separating from the magnetic layer of the tape then triggersthe production of seized deposits with a high adhesive strength on thesliding surface of the magnetic head. These seized deposits cannot beremoved by a simple solvent and wiping action, and therefore graduallyaccumulate, creating a spacing loss between the magnetic head andmagnetic tape that results in reduced output characteristics.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a headcleaning device which solves these problems.

The present invention has been developed with a view to substantiallysolving the above described disadvantages and has for its essentialobject to provide an improved head cleaning device.

In order to achieve the aforementioned objective, a head cleaning deviceused for cleaning the circumference surface of a magnetic head of amagnetic recording and reproducing apparatus to prevent and remove brownstain formed thereon, said device comprises cleaning roller means havingof a soft material; and support means for rotatably supporting saidcleaning roller means along an axis thereof and pressing said cleaningroller means with a predetermined rotational resistance against thecircumference surface of said magnetic head such that the circumferencesurface of said cleaning roller cleans the circumference surface of saidmagnetic head while said cleaning roller means is rotated by saidmagnetic head in rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clear from the following description taken in conjunction withthe preferred embodiments thereof with reference to the accompanyingdrawings throughout which like parts are designated by like referencenumerals, and in which:

FIG. 1A is a schematic perspective view showing a head cleaning deviceaccording to a first embodiment of the present invention,

FIG. 1B is an enlarged perspective view showing the cleaning roller thehead cleaning device shown in FIG. 1A,

FIG. 2 is a cross-sectional view taken along a line II--II shown in FIG.1A,

FIGS. 3A, 3B, 3C, and 3D are graphs schematically showing variousconstitutions of the material used for the cleaning roller according tothe present invention,

FIG. 4 is a schematic perspective view showing a head cleaning deviceaccording to a second embodiment of the present invention,

FIG. 5 is an enlarged perspective view showing the cleaning roller ofthe head cleaning device shown in FIG. 4,

FIG. 6 is a cross-sectional view taken along a line VI--VI shown in FIG.5,

FIG. 7 is a schematic perspective view showing a head cleaning deviceaccording to a third embodiment of the present invention,

FIG. 8 is a schematic perspective view showing a head cleaning deviceaccording to a fourth embodiment of the present invention,

FIG. 9 is a schematic perspective view showing a head cleaning deviceaccording to a fifth embodiment of the present invention, and

FIG. 10 is a graph in assistance of explaining the method forimpregnating the cleaning agents in the cleaning roller according to theprevent invention, and

FIG. 11 is a block diagram showing the head cleaning device according tothe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Referring to FIG. 1A, a head cleaning device according to a firstembodiment of the present invention used for magnetic recording andreproducing apparatus (not shown) is shown. The head cleaning device isprovided beside a magnetic head 2 incorporated in a circumferencesurface of a rotating head cylinder 1. The head cleaning device includesa cleaning unit 5 comprising a cleaning roller 3 and a roller supportmember 4. The roller support member 4 rotatably holds the cleaningroller 3 and can moves in the direction indicated by an arrow A. Thecleaning roller 3 is pressed against the circumference surface of thehead cylinder 1 to remove brown stains BS (seized deposit to) formed onthe magnet head surface 2.

Referring to FIG. 1B, an enlarged perspective view of an example of thecleaning roller 3 is shown. The cleaning roller 3 comprises acylindrical cleaning member 3a and a holder member 3d provided insidethe cleaning member 3a. The constitutions of cleaning member 3a isdescribed later with reference to FIGS. 3A, 3B, 3C, and 3B.

Referring to FIG. 2, a cross-sectional view of the cleaning unit 5 isshown. The roller support member 4 includes an elongated support arm 4a,a shaft 4b provided vertically from an inside surface 4f of the supportarm 4a. The shaft 4b is provided with a notched portion 4d formed on itscircumference surface at the position away from the support arm 4a. Thecylindrical cleaning member 3a is embedded in the holder member 3d, asshown in FIG. 2, and is firmly secured therein. It is needless to saythat the cleaning and holder members 3a and 3b can be formed in anyother suitable configuration, for example, of two concentric tubes whichis shown in FIG. 6. At both opposite ends of the holder member 3d,formed are openings 3e which are mutually connected by a tubular holeextending in alignment with the axis of the holder member. The tubularhole has a diameter smaller than that of the openings 3e but larger thanthat of the shaft 4b.

The holder member 3d is applied with a mini bearing 4c fitted in each ofthe openings 3e and is set to the support arm 4a such that the shaft 4binserts the tubular hole as the notched portion 4d thereof extrudes fromthe holder member 3d. A stop pin 4e is engaged to the notch portion 4dso as to press and secure the cleaning roller 3 to the support arm 4a.Since the end surface of the holder member 3d is kept in press contactwith the inside surface 4f of the support arm 4a by the stop pin 4e, africtional force is available therebetween. This frictional force willact as a resistant force when the cleaning roller 3 rotates along theshaft.

Referring to FIGS. 3A, 3B, 3C, and 3D, schematic enlarged view showingconstitutions of the material used for cleaning member 3a for variousapplication are shown.

As shown in FIG. 3A, the cleaning member 3a is substantially comprisedof a soft material such as felt fibers 3z.

In FIG. 3B, the cleaning member 3a used for removing the seized deposits(brown stain) from the head surface 2 is shown. The soft material 3a isimpregnated with polymer resin 3b and abrasive particles 3c such thatthe abrasive particles 3c are held by the polymer resin 3b to the feltfibers 3z. Thus held abrasive particles 3c can grind off the brown stainformed on the head surface 2 by rubbing the head surface with thecleaning member 3a.

In FIG. 3C, the cleaning member 3a used for preventing the formation ofbrown stain on the head surface 2 is shown. The soft material 3a isimpregnated with a lubricant 3f having an excellent lubricating actionunder low humidity conditions. Examples of such lubricants 3f includefatty acids, fatty acid esters, perfluoro carbonic acid, and perfluoropolyether. To stably complement the lubricating action over long-termcontact during magnetic tape to magnetic head travel, the lubricant 3fis preferably in a liquid state under the normal operating temperaturefor magnetic tape travel, i.e., is in a liquid state at temperaturesless than 40° C.

In FIG. 3D, the cleaning member 3a also used for removing the seizeddeposits from the head surface 2 is shown. In this application, thecleaning member 3a has a constitution combined by those shown in FIGS.3B and 3C. The soft material 3a is impregnated with polymer resin 3b,abrasive particles 3c, and lubricant 3f. The lubricating action of thelubricant 3f reduces the coefficient between the abrasive particles 8cand the magnetic head surface 2 and enable to grind off the brown stainin a milder manner when compared with the cleaning member 3a of FIG. 3B.

In operation, the cleaning unit 5 moves in the arrow direction A topress the cleaning roller 3 having the above constitutions against thecircumference surface of the head cylinder 1 in rotation. By thecircumference surface of the head cylinder 1, the cleaning roller 3 isdriven to rotate along the shaft 4b. However, the friction between thesupport arm 4a and the holder member 3d acts as the resistant forceagainst the rotation of cleaning roller, as described above. Thisresistance force enables the cleaning roller 3 to rub the cylindersurface 1 with a suitable force for cleaning the head 2.

Second Embodiment

Referring to FIGS. 4, 5, and 6, a head cleaning device according to asecond embodiment of the present invention is shown. In this embodiment,head cleaning device has a construction similar to that of the firstembodiment, but the cleaning roller 3 has a cleaning member 3a comprisedof first and second cleaning portions 3g and 3f. The first cleaningportion 3g is made by soft material impregnated with the abrasiveparticles 3c and polymer resin 3b, as described above with reference toFIG. 3B, and is used to remove the brown stain BS from the head surface2. The second cleaning portion is made my the soft material with noimpregnation as described above with reference to FIG. 3A, and is usedfor wiping off residual deposits and abrasive particles 3c which maydropped from the first cleaning portion 3g.

As best shown in FIG. 5, the first and second cleaning portions 3g and3h are sharing the single cleaning member 3a by dividing the cleaningmember 3a in two portions extending in the axial direction thereof. Thecleaning member 3a is divided into first and second cleaning portions 3fand 3g FIG. 5. Although it is shown that the first cleaning portion 3goccupies larger portion than the second cleaning portion 3f in FIG. 5,it is possible to divide first and second portion at an optional ratioaccording to the application purpose.

In FIG. 6, the right half area of the cleaning member 3a shows the firstcleaning portion 3g the constitution, and the left half shows the secondportion 3h having the constitution shown in FIG. 3A.

In this embodiment, since the two portions 3g and 3h having differentcleaning functions are formed in a single unit of the cleaning roller 3,selecting the ratio of the two portions can control the operation ratioof brown stain removing and wiping off to obtain optimum cleaningresult.

Third Embodiment

Referring to FIGS. 7 and 8, a head cleaning device according to a thirdembodiment of the present invention is shown. In this embodiment, thehead cleaning device comprises first and second cleaning units 5a and 5bprovided separately. The first cleaning unit 5a includes a firstcleaning roller 3g' comprised of the same material as the first cleaningportion 3g which is used for removing the brown stain according to thesecond embodiment. The second cleaning unit 5b includes a secondcleaning roller 3h' comprised of the same material as the secondcleaning portion 3h which is used for wiping off the residual depositsand abrasive according to the second embodiment. The cleaning rollers3g' and 3h' are also supported by first and second support members 41and 42.

Since the first and second cleaning units 5a and 5b can moveindependently from the other, it is possible to apply the units 5a and5b to the head cleaning operation at a desirable ratio of operation,resulting in the optimum cleaning effect.

Fourth Embodiment

Referring to FIG. 9, a head cleaning device according to a forthembodiment of the present invention is shown. In this embodiment, thehead cleaning device comprises first and second cleaning units 5a' and5b' which have constructions similar to those of the third embodiment,but first and second support members 41' and 42' are integrally combinedat the distal ends thereof from the cleaning rollers 3g' and 3h'generally in a V-shaped configuration. The combined cleaning units 5a'and 5b' are rotatably supported by a roller support member 20 at theapex portion of cleaning units 5a' and 5b'. By only this support member40, the combined cleaning units 5a' and 5b' are moved in the arrowdirection A, resulting in that the space required for these mechanismcan be reduced and the recording and reproducing apparatus can be madecompact. Furthermore, even if both rollers 3g' and 3h' fails to contactto the cylinder surface 1 evenly at the start of the cleaning, thecombined cleaning units can swing with respect to the support 40 and areautomatically repositioned to contact to the cylinder surface evenly.

In each of the above embodiments, a humidity sensor 6 is provided fordetecting the humidity around the cylinder 1 and produce a humiditysignal Sh indicative of the detected humidity. This humidity sensor 6 isutilized such that the head cleaning device according to the presentinvention will start cleaning operation when the detected humidity isbelow a predetermined value, for example 40%, to prevent or remove thebrown stains forming on the magnetic head 2, as described bellow.

Referring to FIG. 11, a block diagram of the head cleaning deviceaccording to the present invention is shown. The head cleaning deviceincludes a comparator 50 for comparing the humidity signal Sh with thereference humidity Sr. A driver 53 is provided for driving the cleaningunit 5. A controller 52 is provided for controlling the driver 53 basedon the output form the comparator such that the cleaning unit 5 movestoward the magnetic head surface 2 for cleaning thereof when thedetected humidity (Sh) is less than the reference humidity (40%).

It is also possible that the operation of this abrasive action cleaneris started when a deterioration in performance associated with thechange in electromagnetic conversion characteristics caused by depositsseizing on the magnetic head surface is detected.

It is to be noted that for first and second cleaning units 5a and 5b toperform the desired operation, the surface of the cleaning rollers 3must be kept clean. Therefore, to avoid having the same part of eachcleaning member always sliding against the magnetic head, a mechanismfor moving the cleaning member axially to the cylinder can be provided.One example of such mechanism is proposed by the above described U.S.Pat. No. 5,012,376. Furthermore, it will be obvious to those skilled inthe art that such a mechanism is necessary to continuously achieve thesubstance of the invention.

Referring to FIG. 10, a method to have the soft material 3a of thecleaning roller 3 impregnated with cleaning agents such as polymerresins 3b, abrasive particles 3c, or lubricants 3f is shown. Acylindrically shaped soft material 3a is immersed for a specified periodof time in a solution 7 of polymer resin, abrasive particles, andsolvent; hardener, antistatic agent, and dispersing agent may be alsoused in the solution 7 as required. When the soft material 3a comprisesfirst and second cleaning portions, 3g and 3h for example, that part ofthe soft material 3a immersed in the solution 7 pooled in a container 3ibecomes the first cleaning portion 3g, and the unimmersed part becomesthe second cleaning portion 3h. To form the first cleaning portion 3g,the soft material 3a of diameter D is immersed to a predeterminedimmersion depth h; it will be obvious that the depth h is smaller thanthe diameter D. This immersion depth h is the variable determining theabrasive effect of the first cleaning member, and is also related to thespecifications of the magnetic recording and reproducing apparatus inwhich the cleaner is provided.

The solution 7 is prepared in a mixer to assure sufficient mixing anddispersion. Any of many difference mixers may be used, including ballmills, sand mills, dissolvers, attriter, high speed mixers, kneaders,Henschel mills, and planetarium mixers.

The polymer resin may be fibrous resins such as nitrocellulose orcellulose acetobutyrate, polyvinyl chloride-acetate copolymer,polyvinylidene chloride, polyurethane, polyamide, urea resin, epoxyresin, polyester resin, fluororesin, acrylonitrile, phenol resin, or acombination of two or more of these or their derivatives considering thedispersion characteristics of the resin.

Possible hardeners include monomeric isocyanate, polyamine, andpolyamide.

Possible solvents include methyl ethyl ketone, methyl isobutyl ketone,toluene, cyclohexanone, ethyl acetate, THF (Tetrahydrofuran),DMF(N,N-Dimethylformamide), and isopropyl alcohol.

Antistatic agents include carbon black and graphite powder.

Dispersing agents, including higher fatty acid, higher fatty acid metalsalts, higher fatty amide, higher alcohol, phosphoric ester, glycerine,silane coupling agents, and titanium coupling agents, may be added asrequired.

Preferable soft materials include felt, sponge, nonwoven fabric,deerskin, and wool. It is further preferable for the softness of thematerial to be retained after impregnation with the polymer resin andabrasive particles by immersion in the above solution. The preferableshape is a cylindrical shape to assure long-term uniform contact withthe magnetic head.

Artificial felt materials include polyethylene terephthalate, polyesterssuch as polyethylene, naphthol, polyethylene, polypropylene and otherpolyolefins, cellulose acetate, cellulose diacetate, cellulose acetatebutyrate, cellulose acetate propylate, and other celluloses derivatives,polyvinyl chloride, polyvinylidene chloride, and other vinyl resinpolycarbonates, polyimide, polyether imide, polyamide imide, and otherplastics.

Nonwoven fabric materials include polyester, nylon, crimped nylon,acrylic, vinylon, rayon, and cotton.

Abrasive particle materials include a alumina (Al₂ O₃), titanium oxide(TiO₂), iron oxide (Fe₂ O₃), chromium oxide (Cr₂ O₃), silicon carbide(SiC), and silicon oxide (SiO₂).

It is also possible to separately prepare the first and second cleaningmembers, and then glue them together using an adhesive. This method isalso well within the scope of the present invention.

When the soft material 3a itself is formed of glued resins, immersion ofthe soft material 3a in a solution 7 containing organic solvent maydissolve the resin and reduce the characteristics softness of a softmaterial. When using such a soft material 3a, it is therefore necessaryto adjust the type and quantities of materials used in the polymer resin3b and the solvent(s) in the solution 7. Note that if water is used asthe solvent, this problem will not occur.

It is to be noted that the head cleaning roller 3 is comprised tosustain the performance of a soft material even after impregnation withthe abrasive particles 3c, but because the head cleaner 3 contacts thehead cylinder 1 on which the magnetic head is mounted in addition tocontacting the magnetic head, there are also irregular cases wherein thehead cleaner 3 may impart mechanical damage to the head cylinder 1surface. To prevent this, a hard thin film such as SiC, Al₂ O₃, BN,Ti-N, Cr-N, or DLC (diamond carbon) may be formed on the cylindersurface.

The head cleaning devices according to the present invention havingcleaning roller 3 prepared under the various conditions areexperimented, thorough which the following results are observed.

First experiment

The head cleaning device according to the first embodiment is used inthis experiment. A cleaning roller 3 comprised of polyester felt 3ameasuring 10 mm outside diameter and 5 mm inside diameter with a 15 mmcylinder length was immersed in a solution of alumina particles andurethane resin dispersed in solvent to impregnate the felt with thealumina particles and urethane resin.

The weight ratio of this mixture of alumina, urethane resin, and solventis shown below.

    ______________________________________                                        α alumina  10         parts                                             polyurethane      1         part                                              Solvent:                                                                      cyclohexane      30         parts                                             toluene          60         parts                                             methyl ethyl ketone                                                                            90         parts                                             ______________________________________                                    

After immersion the felt in this solution, curing was promoted at 60° C.for 12 hours. A head cleaning roller 3 in which this impregnated felt 3awas mounted on the holder member 3d was then installed in a magneticrecording and reproducing apparatus equivalent to a commercial VHS videodeck. Using a 120-min. length metallic magnetic powder-type magnetictape, a 100-cycle repeated playback test (equivalent to an approximately200 hr. playing time) was performed to investigate the change in theplayback characteristics.

This test was conducted under typical low humidity conditions,specifically at a 23° C. ambient temperature and 10% relative humidity.The magnetic head used in the test has a metal magnetic core, and thewavelength of the recorded signal was 0.7 μm. The rotating rollersupport member 4 supporting the cleaning roller 3 was intermittentlymoved near the magnetic head 2 by means of a timer circuit (not shown)and intermittant application of power to a solenoid (not shown)connected to the rotating roller support member 4, thereby contactingthe head cleaning roller 3 to the magnetic head 2 for a predeterminedperiod.

The contact time between the head cleaning roller 3 and magnetic head 2in the head cylinder 1, i.e., the operating time, in this test of thefirst embodiment was 3 sec., and the no-contact time between the headcleaner 3 and magnetic head 2, i.e., the standby time, was 30 min. Theduration of each mode is determined by the density and materials of thepolymer resin 3b and abrasive particles 3c used in the head cleaner 3,the pressure of the head cleaning roller 3 on the magnetic head 2, andthe operating environment, i.e., the temperature and humidity. Theresults of this repeated tape travel test are shown in Table 1 bellow.

                  TABLE 1                                                         ______________________________________                                                  Output  Seizing of Clogging                                                   drop (dB)                                                                             brown stains                                                                             (sec.)                                           ______________________________________                                        First experiment                                                                          -0.5      none       approx. 1 to 3                               Second experiment                                                                         -1.5      minimal    approx. 3                                    Comparison 1                                                                              -3.5      sever      10 Min.                                      ______________________________________                                    

"Output drop" expresses the output measured after the 100-cycle repeatedplayback test described above referenced to the output measured beforethe experiment.

"Seizing" indicates the presence of seized deposits (brown stain) on themagnetic head surface after the 100-cycle repeated playback test whenobserved under an optical microscope at a 200X magnification ratio.

"Clogging" is the total time of clogging observed during the repeatedplayback test.

"Comparison 1" shown in Table 1 shows a result obtained from anexperiment performed on a magnetic recording and reproducing apparatuscomprising a conventional head cleaning device, i.e., a felt cleaningroller is not impregnated with the alumina particles and urethane resin.In "Comparison 1", the head surface is only wiped by the conventionalcleaning device under the same test conditions as first and secondexperiments.

Based on the results shown in Table 1, it is clear that seized depositson the sliding surface of the magnetic head can be removed, and that theoutput drop and clogging resulting from the occurrence of seizeddeposits on the magnetic head are minimal when the cleaner is a feltmember impregnated with alumina particles and urethane resin.

Second experiment

The head cleaning device according to the first embodiment is used inthis experiment. The cleaning roller 3 was prepared by immersing thefelt soft material in a solution of perfluoro polyether liquid dispersedat room temperature (25° C.) in isopropyl alcohol at 1500 ppm.Essentially the same repeated playback test conducted with the firstembodiment described above was conducted, and the results are shown inTable 1. While the output drop was -1.5 dB and a minimal quantity ofseized deposits was observed with this cleaner 3, there was still asignificant reduction in seized deposits and a reduction in cloggingrelative to "Comparison1".

Third experiment

The head cleaning device according to the second embodiment is used inthis experiment. The cleaning roller 3 having first and second cleaningportions 3g and 3h was prepared by the method shown in FIG. 10, i.e.,using a variable immersion depth h of the cylindrical felt member 3a inthe solution 7. The solution described in the first experiment above wasused for the solution 7. The repeated playback test described in thefirst experiment was also conducted. In addition to the items evaluationin the first experiment, the dropout characteristic was also measuredadditionally.

This dropout refers to a signal loss of -16 dB or greater for a periodof 15 μsec or longer expressed as the number of dropouts counted perunit time. Using a variable immersion depth h, the test results areshown in Table 2 as "Third experiment".

                                      TABLE 2                                     __________________________________________________________________________           1st Cleaning Unit                                                                          2nd Cleaning Unit                                                     Operation Mode                                                                        Operation Mode                                                                         Result                                                  Immersion                                                                          TO  TS  TO   TS  Output  Clogging                                                                           Drop Out                            Experiment                                                                           Depth h                                                                            (Sec)                                                                             (min)                                                                             (Sec)                                                                              (min)                                                                             (-dB)                                                                             Seizure                                                                           (sec)                                                                              (/min)                              __________________________________________________________________________    Third  3    1   30  2    30  1.5 minimal                                                                           0.5  40                                         7    2   30  1    30  0.5 none                                                                              0.5  30                                         10 Min.                                                                            3   30  --   --  0.5 none                                                                              1-3  50                                  Fourth 10 Min.                                                                            3   30  3    30  0.5 none                                                                              1    40                                         10 Min.                                                                            1   10  3    30  0.5 none                                                                              0.3  10                                  Fifth  10 Min.                                                                            3   30  3    30  0.5 none                                                                              1    40                                  Comparison 1                                                                         --   --  --  3    30  3.5 severe                                                                            10 Min.                                                                            100 Min.                            __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________           1st Cleaning Unit                                                                          2nd Cleaning Unit                                                     Operation Mode                                                                        Operation Mode                                                                         Result                                                  Immersion                                                                          TO  TS  TO   TS  Output  Clogging                                                                           Drop Out                            Experiment                                                                           Depth h                                                                            (Sec)                                                                             (min)                                                                             (Sec)                                                                              (min)                                                                             (-dB)                                                                             Seizure                                                                           (sec)                                                                              (/min)                              __________________________________________________________________________    Sixth  10 Min.                                                                            3   30  --   --  0.5 none                                                                              1-3  50                                  Comparison 2                                                                         10 Min.                                                                            3   30  --   --  3.5 severe                                                                            10 Min.                                                                            100 Min.                            __________________________________________________________________________

The results obtained with that an immersion depth h is greater than 10are shown in the first experiment above. When the first and secondcleaning members are simultaneously prepared in the felt member using avariable immersion depth h, clogging and dropout can be furtherimproved.

In table 2, "TO" expresses the operation period while the cleaningrollers are pressed against the circumference surface of head cylinder 1for cleaning the magnetic head 2.

"TS" expresses interval period between each operation cleaning operationof the cleaning roller

Forth experiment

In this experiment, the head cleaning device comprising separate firstand second cleaning units 5a and 5b according to the third embodiment ofthe present invention was prepared. The first cleaning roller 5a was afelt member impregnated with abrasive particles and polymer resin at animmersion depth h≧10 to impart an abrasive action as in the firstembodiment. The second cleaning member providing the residual depositwiping function was prepared with an immersion depth h=0, i.e.,unimmersed in the solution 6. The same repeated playback test describedin the first experiment was conducted. As shown by the results under theforth experiment 4 in Table 2, seizing, clogging, and drop-out areimproved relative to "Comparison 1".

Fifth experiment

In this experiment, the cleaning device comprising discrete first andsecond cleaning members 5a and 5b supported by a common rotating rollersupport member 40 according to the fourth embodiment of the presentinvention was used. The same repeated playback test conducted in thefirst experiment was again performed.

As will be known from the results for this experiment shown in Table 2,improvements in seizing, clogging, and dropout relative to "Comparison1" are obtained. It is to be noted that this fifth experiment offers theadditional benefit or requiring less space than does the fourthexperiment because the first and second cleaning members 5a and 5b aresupported by a single rotating roller support member 40.

Sixth experiment

In this experiment, the head cleaning device according to the firstembodiment is used. The cleaning roller 3 was prepared using polyvinylalcohol as the polymer resin, α alumina for the abrasive particles, andwater as the solvent in the immersion solution 7 at the following weightratio.

    ______________________________________                                        α alumina  3          parts                                             polyvinyl alcohol                                                                              1          part                                              water           50          parts                                             ______________________________________                                    

The cleaning roller is made of soft material of nonwoven fabriccomprising rayon and acetate at a 1:1 ratio with acrylate as the binderwas immersed in this solution 7. The same repeated playback testdescribed in the first embodiment was again performed. The results areshown in Table 3.

"Comparison 2" shown in Table 3 shows the results for a head cleaningdevice comprising the cleaning roller made of the nonwoven soft clothused in the sixth experiment and is immersed in the solution 7 of thefirst experiment. It is obvious that the cleaner prepared with anonwoven fabric obtains the same effects achieved with the cleaner ofthe first experiment. With the cleaning roller of "Comparison 2",however, the binder is dissolved by the organic solvent, resulting inirregular disruption of the fibers and loss of functionality as a softmaterial. Specifically, because the cleaner does not contact themagnetic head with a soft touch, the desired effect is not obtained inthe applied magnetic recording and reproducing apparatus.

With the cleaning roller prepared according to the sixth experiment,however, no change is observed in the binder of the nonwoven fabric evenafter immersion in the solution 7, and the cleaner can thereforefunction as a soft material with an abrasive action.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A head cleaning device used for cleaning thecircumference surface of a rotating magnetic head of a magneticrecording and reproducing apparatus to prevent and remove brown stainformed thereon, said device comprising:cleaning roller means having asoft material, said soft material being impregnated with abrasiveparticles such that the abrasive particles are distributed throughoutthe soft material by adhering to fibers on the surface and internal tothe soft material; support means for rotatably supporting said cleaningroller means along an axis thereof and pressing said cleaning rollermeans with a predetermined rotational resistance against thecircumference surface of said magnetic head such that the circumferencesurface of the cleaning roller means cleans the surface of said magnetichead while said cleaning roller means is rotated by said magnetic headin rotation; driver means for driving said support means to press saidcleaning roller means against said magnetic head; humidity sensor meansprovided beside said magnetic head for detecting humidity therearound toproduce a humidity signal; comparator means for comparing said humiditysignal with a predetermined reference humidity; and controller means forcontrolling said driver means when said humidity signal is less thansaid predetermined reference humidity.
 2. A head cleaning device usedfor cleaning the circumference surface of a rotating magnetic head of amagnetic recording and reproducing apparatus to prevent and remove brownstain formed thereon, said device comprising:cleaning roller meanshaving a soft material; support means for rotatably supporting saidcleaning roller means along an axis thereof and pressing said cleaningroller means with a predetermined rotational resistance against thecircumference surface of said magnetic head such that the circumferencesurface of the cleaning roller means cleans the surface of said magnetichead while said cleaning roller means is rotated by said magnetic headin rotation; driver means for driving said support means to press saidcleaning roller means against said magnetic head; humidity sensor meansprovided beside said magnetic head for detecting humidity therearound toproduce a humidity signal; comparator means for comparing said humiditysignal with a predetermined reference humidity; andcontroller means forcontrolling said driver means when said humidity signal is less thansaid predetermined reference humidity.
 3. A head cleaning device usedfor cleaning the circumference surface of a rotating magnetic head of amagnetic recording and reproducing apparatus to prevent and remove brownstain formed thereon, said device comprising:first cleaning roller meanshaving a soft material impregnated with abrasive particles for removingsaid brown stain; first support means for rotatably supporting saidfirst cleaning roller means and movable in a first predetermineddirection to press said first cleaning roller means with a firstpredetermined rotational resistance against the circumference surface ofsaid magnetic head such that the circumference surface of said firstcleaning roller means cleans the circumference surface of said magnetichead while said first cleaning roller means is rotated by said magnetichead in rotation; second cleaning roller means having a soft materialfor wiping off said magnetic head surface; second support means forrotatably supporting said second cleaning roller means and movable in asecond predetermined direction to press said second cleaning rollermeans with a second predetermined rotational resistance against thecircumference surface of said magnetic head such that the circumferencesurface of said second cleaning roller means cleans the circumferencesurface of magnetic head while said second cleaning roller means isrotated by said magnetic head in rotation; driver means for moving saidfirst and said second support means to press said first and said secondcleaning roller means against said magnetic head; humidity sensor meansprovided beside said magnetic head for detecting humidity therearound toproduce a humidity signal; and controller means responsive to saidhumidity signal for controlling said driver means.
 4. A head cleaningdevice as claimed in claim 3, wherein said abrasive particles aredistributed throughout the soft material by adhering to fibers on thesurface and internal to the soft material.
 5. A head cleaning device asclaimed in claim 4, wherein said combined first and second support meansswing with respect to said combined end.
 6. A cleaning head device asclaimed in claim 3, wherein said first and said second support means areintegrally combined at distal ends thereof from said first and secondroller means such that said first and said second predetermineddirections are identical.
 7. A head cleaning device as claimed in claim3, wherein said first and said second support means move independentlyfrom the other.
 8. A head cleaning device as claimed in claim 3, furthercomprising comparator means for comparing said humidity signal with apredetermined reference humidity.
 9. A head cleaning device as claimedin claim 8, wherein said controller means controls said driver meanswhen said humidity signal is less than said predetermined referencehumidity.
 10. A head cleaning device as claimed in claim 9, wherein saidreference humidity is 40%.